Question: Who is the spouse of Bohdan Khmelnytsky before 1651-0-0?
Paraphrase: Who is Bohdan Khmelnytsky's wife?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q203808 p:P26 ?s . ?s ps:P26 ?obj . ?s pq:P582 ?x filter(contains(YEAR(?x),'1651')) }